Apparatus for Thermal Vapor Coating an Article

ABSTRACT

Apparatus for thermal vapor coating an article comprises a pair of spaced fixed diaphragms and a disc having inclined channels along its periphery rotating between said fixed diaphragms for defining the steam jet impinging on the article mounted in a vacuum chamber. The inclination of the channels is such that the direct path of the jet stream between the vaporization source and the article is blocked. The rotational speed of the disc is determined as a function of the angular inclination of the channels as well as the variable velocity of the steam jets.

United States Patent n 1 Horn et a1.

1 1 APPARATUS FOR THERMAL VAPOR COATING AN ARTICLE [76] Inventors:I-Ierwig Reinholder Horn; Adolf Florian Aldrian, both of Steyrergasse17, Graz, Austria 22 Filed: Nov. 19, 1973 21 Appl. No.: 417,408

[52] U.S. CI 118/49; 55/407 [51] Int. Cl. C23c 13/08 [58] Field ofSearch ll8/4849.5; 55/17, 407

[56] References Cited UNITED STATES PATENTS 3,277,637 10/1966 lobner55/17 X FOREIGN PATENTS OR APPLICATIONS 293,814 10/1971 Austria ..l18/49[4 1 May 20, 1975 Primary ExaminerMorris Kaplan Attorney, Agent, orFirm-Wats0n, Cole, Grindle & Watson [57] ABSTRACT Apparatus for thermalvapor coating an article comprises a pair of spaced fixed diaphragms anda disc having inclined channels along its periphery rotating betweensaid fixed diaphragms for defining the steam jet impinging on thearticle mounted in a vacuum chamber. The inclination of the channels issuch that the direct path of the jet stream between the vaporizationsource and the article is blocked. The rotational speed of the disc isdetermined as a function of the angular inclination of the channels aswell as the variable velocity of the steam jets.

4 Claims, 3 Drawing Figures PATENIED MAY 2 0 I975 SHEET 18F 2 F/afAPPARATUS FOR THERMAL VAPOR COATING AN ARTICLE This invention relates tothermal vapor coating and in particular to apparatus whereby suchprocesses can be carried out and wherein structure is provided toseparate the radiation emitted from a thermal vaporization source andthe steam jet.

Austrian Pat. No. 231,530 describes a process for carrying out a methodof thermal vapor coating with a lower thermal load on the supportmaterial that is to be vapor coated. The essence of such a processresides in the fact that the heat radiation emanating from a thermalvaporization source is separated from the jets of steam because of itsgreater dimensional speed. The aforementioned patent also describesapparatus for carrying out the vapor coating process.

In general, apparatus for thermal vapor coating comprise a rotatinghollow cylinder having slots on its peripheral surface and the cylinderis mounted relative to the thermal vaporization source and is rotated atsuch a speed so that the separation of the heat radiation from thecorpuscular radiation will be achieved for the above mentioned purpose.Further, other apparatus are known which comprise the system of rotatingdiscs and oscillating diaphragm slides.

Austrian Pat. No. 293,814, which also discloses apparatus for carryingout thermal vapor coating processes, discloses an arrangement in whichthe diaphragm slots follow each other in a known manner along thedirection of the rotational axis of the system and wherein the diaphragmelements comprise a multiplicity of channels for the passage of steam.The channels are formed along the generatrix of a cylinder around acommon axis which is inclined relative to the steam jet at such an anglethat a direct passage in the direction of the jets is obstructed.

Such a system has a serious disadvantage in that it requires a very highr.p.m., in the order of approximately 50,000 r.p.m., which causesproblems for the associated vacuum arrangement. However, it should benoted that the required r.p.m., within wide limits, is merely a functionof the size of the surface that is to be vapor coated and thus such adisadvantage applies to all of the known prior art thermal vapor coatingsystems.

A thermal vapor coating system must take into consideration, among othermatters, the substrate that is to be vapor coated and that normally thesubstrate is mounted perpendicularly above the source of thevaporization. Consequently, in small installations as are quite oftenused, especially in the case of electron microscopy, only a limitedspace is available for the mounting of the necessary components of thesystem.

The method and apparatus in accordance with this invention take intoconsideration all of the above factors. One of its advantages over theknown arrangement is that it requires considerably less space andtherefore the apparatus cannot only be installed in customarily usedtreatment installations, but enables the vaporization source to be movedin closer proximity to the substrate as is likewise frequentlynecessary. The last mentioned consideration also requires that theheight of the rotating cylinder be kept as low as possible. Thisconsideration, in turn, requires a stronger slant or angularization ofthe rotating diaphragm relative to its rotational axis. Such a largeangle, however,

cannot be realized by merely inclining the axis in those cases where theslots are parallel to the axis.

Further, the invention has the advantage that it makes possible coatingprocesses in a high vacuum with reduced thermal load of the substrate,whereby the structure has a very low height based on the specialconstruction of its diaphragm system and can also otherwise be inserteddirectly into customary preparation installations.

The arrangement, according to the invention, is characterized in thatthe inlet and outlet slits of the dia phragm system are developed in amanner known per se, that is, as screw surfaces around the rotationalaxis of the diaphragm system; however, the optical direct vision in thedirection of the rays of steam is interdicted.

A primary object of the present invention is to provide improved thermalvapor coating apparatus which enables a considerable reduction in thesize of the coating apparatus.

Another object of the invention is to provide an apparatus of the typespecified in which the source of vaporization may be closely adjacent tothe substrate to be coated.

A further object of the invention is to provide an improved apparatus ofthe type specified in which the rotational speed of the cylinder isconsiderably reduced.

The above, as well as other, objects and advantages will be apparentfrom the following description taken in conjunction with the drawingswherein:

FIG. 1 is a sectional view illustrating the essential components of theapparatus which are connected to a pump system for creating a highvacuum;

FIG. 2 shows a cross-section view the rotating and fixed diaphragmmembers of the apparatus; and

FIG. 3 shows an elevational view of a portion of the rotating and fixeddiaphragm members of the apparatus.

The steam jets 9 emitted from vaporization source 1 are reduced by fixeddiaphragms 2, 4 to the required cross section or size of the suspendedelement 5. Between fixed diaphragms 2, 4, cylinder 3 is mounted torotate about a vertical axis and includes channels 8 along itsperiphery. The geometry of the channels is selected so that in the areaof the reduced steam jet there is no direct line of sight betweenvaporization source 1 and the suspended element 5. Channels 8 are in theform of helical surfaces having a helix angle a (as illustrated in FIG.2) with the transverse axis of cylinder 3. Thus, channels 8 are helicalwhich provide passages for steam jets 9. Cylinder 3 and its associatedchannels 8 thus form a rotating diaphragm between fixed diaphragms 2, 4.

The material to be coated represented by numeral 5 is suspended withinvacuum chamber 6 in alignment with the slits in fixed diaphragms 2 and4. Motor 7 is provided to rotate cylinder 3. The entire apparatusillustrated in FIG. 1 is connected to a pump system for creating a highvacuum within chamber 6.

The peripheral speed V of channels 8 is a function of the angle a aswell as variable velocity 0 of the steam jets. Angle a is in turn afunction of the values b, B, s, d and h of the optical impermeability ofthe channels. The cross-section of the vapor spray and thus the area tobe evaporation-coated is defined by the magnitudes of B, b, S. B and bmay be varied as required but only in such a manner that the relation isfulfilled.

If no light should enter into the defined area, the separation of thechannels must be'.

A smaller separation 3 would provide an unnecessary number of channelswhile a greater value of 1: would allow the light to enter into thedefined area.

It will be recognized that the following formulas apply to the apparatusof FIG. 1:

1. Tangent a We 2. From the above formula, V='c tE oz 3. The r.p.m. ofthe cylinder is n (60/11') (V/D) Assuming that D equals 0.2 m and a thenformula 3 indicates that n 60/17 V/D which equals (60hr) (Fig a/D) whichequals 'F. From the above relationship and the fact that the steam jetshave velocities of between 100 and 1,000 M/s, the r.p.m. of the cylinderor rotating diaphragm will be from between 2,500 and 25,000 revolutionsper minute. Such R.p.ms. are easily realizable with state-of-the-artequipment even in high vacuums.

The symbols used in FIG. 2 and the above formulas are defined asfollows:

V peripheral speed of cylinder 3 F average velocity of the steam jet Dcylinder diameter n r.p.m. of the cylinder at angle of channels 8 dseparation of channels b width of slit opening in fixed diaphragm 2 Bwidth of slit opening in fixed diaphragm 4 s opening of the channels hheight of the cylinder S depth of the channels What is claimed is:

1. Apparatus for thermal vapor coating an article, comprising:

a vaporization source for generating jets of steam including the coatingsubstance;

a vacuum chamber for mounting said article; and

means mounted between said vacuum chamber and said source for directingsaid vapor to said article, said means including a rotating disc havinga number of channels along its periphery, said channels being inclinedwith respect to the longitudinal axis of said disc and said disc beingmounted to rotate so that said channels are positioned in the jet streambetween said source and said article and inclined at an angle to blockthe direct path of said jet stream from said source to said article.

2. Apparatus as in claim 1 wherein said means for directing said vaporto said article further include a pair of spaced diaphragms each havingan aperture for passage of said jet stream and said rotating disc ismounted to pass between said spaced diaphragms.

3. Apparatus as in claim 2 wherein the rotational velocity of said discis a function of the variable velocity of said steam jets and the angleof said channels with respect to the transverse axis of said disc.

4. Apparatus as in claim 3 wherein the rotational velocity of said discis approximately 25 times the velocity

1. Apparatus for thermal vapor coating an article, comprising: avaporization source for generating jets of steam including the coatingsubstance; a vacuum chamber for mounting said article; and means mountedbetween said vacuum chamber and said source for directing said vapor tosaid article, said means including a rotating disc having a number ofchannels along its periphery, said channels being inclined with respectto the longitudinal axis of said disc and said disc being mounted torotate so that said channels are positioned in the jet stream betweensaid source and said article and inclined at an angle to block thedirect path of said jet stream from said source to said article. 2.Apparatus as in claim 1 wherein said means for directing said vapor tosaid article further include a pair of spaced diaphragms each having anaperture for passage of said jet stream and said rotating disc ismounted to pass between said spaced diaphragms.
 3. Apparatus as in claim2 wherein the rotational velocity of said disc is a function of thevariable velocity of said steam jets and the angle of said channels withrespect to the transverse axis of said disc.
 4. Apparatus as in claim 3wherein the rotational velocity of said disc is approximately 25 timesthe velocity of said steam jets.